In this paper, using sub-supersolution argument, we prove an existence result on positive solution for an ecological model under certain conditions. It also describes the dynamics of the fish population with natural predation and constant yield harvesting. The assumptions are that the ecosystem is spatially homogeneous and the herbivore density is a constant which are valid assumptions for mana...

We analyzed the effects of population density and climatic variables on the rate of population growth in the guanaco ( ), a wild camelid species in Lama guanicoe South America. We used a time series of 36 years (1977-2012) of population sampling in Tierra del Fuego, Chile. Individuals were grouped in three age-classes: newborns, juveniles, and adults; for each year a population transition matri...

the main aim of this project was the assessment, for the first time, anthropometrically, the nutritional status in school girls' population aging from 7 to 10 years in ahwaz city and ultimately compare their growth rate with other findings obtained from different part of iran and also with the proposed standards of nchs in this respect. this study was conducted on 1200 apparently healthy school...

The population size in almost all of the countries in the South and Central Asian region shows a significant increase in the last few decades. Nevertheless, during 19801990 and 1990-2000 decades, countries in South Asia experienced a significant decline in the average annual rate of population growth (Table 1). Afghanistan is the only exception showing an increase in the growth rate and its pop...

BACKGROUND Understanding aneurysm growth rate allows us to predict not only the current rupture risk, but also accumulated rupture risk in the future. However, determining growth rate of unruptured intracranial aneurysms often requires follow-up of patients for a long period of time so that significant growth can be observed and measured. We investigate a relationship between growth rate and ru...

Predator–prey interactions play major and direct roles in the structuring of zooplankton communities. Asplanchna usually predates ciliates, rotifers, cladocerans and sometimes even copepods, its predation may drive not only the ecological, but also the evolutionary dynamics of prey populations. In the present study, the life-table demography and the population growth of Asplanchna brightwelli w...

in order  to study the effect of drought stress on some growth indices of oil sunflower cultivars, a study was conducted in isfahan. the experiment was conducted as split plots in a randomized complete blocks design with three replications in isfahan (51° 48' e, 32° 40' n).main plots were drought stress in four levels (80, 100, 120, and 140 mm evaporation from evaporation pan class a and cultiv...

to compare the reproductive performance of the wild and cultured stocks of beluga, huso huso males, some spermatological parameters were measured including: sperm motility, sperm density, spermatocrit and also fertilization rate, hatching rate and larval growth and survival rates. the semen samples were sampled from 11 wild spawners and 12 cultured brooders. a half of each semen sample was allo...